1. The Field of the Invention
The present invention relates to the field of computers. More particularly, it relates to an interface between a connector and a communications card in a computer system, and specifically to a physical/electrical media connector interface for use with a 5 mm PCMCIA-architecture communications card, such as used in laptop and notebook computers.
2. Related Technology
A. Data Transmission
The field of transmission of data by phone lines or network cables is a rapidly expanding field. Users of personal computers in particular are finding such practice to be of great value.
For example, there are numerous public and private networks and databases which store data or programs. Absent the ability to send and receive data over telephone lines through a modem, a user is relegated to relying upon the exchange of discs or tapes in order to receive data suitable for use with their computer.
Similarly, companies performing tasks that are integrated are aided by local area networks ("LANs") which permit personnel to exchange electronically retrievable data. The ability to freely transfer data and information from one computer to another computer over a telephone line may dramatically increase productivity and reduce overall production time.
To translate the binary code utilized by a computer into signals capable of being transmitted over the telephone lines, modems have been developed to translate and reconfigure binary signals into analog signals capable of being transmitted over telephone lines. For conversion of signals to take place, a modem must be placed between the computer generating the binary signals and the telephone line capable of carrying the analog signals.
Typically, in today's practice, a modem at the transmitting computer end of a telephone line receives binary digital data from the computer and converts the binary code received from the computer into modem frequency signals. These modem frequency signals are then transmitted over the telephone lines to a receiving modem at the receiving computer.
The modem at the recipient's end then converts the modem frequency signal back to binary digital data characters and inputs the data characters to the input port of the receiving computer.
As today's modems serve to provide a compatible interface between the phone lines and the computer, the Federal Communications Commission ("FCC") and telephone companies require an interface to moderate all signals or energy being input into the phone lines. This interface protects the phone lines and systems from damage, thereby ensuring the integrity and quality of transmissions over the phone lines.
A required part of this interface is a Data Access Arrangement ("DAA") circuit. The DAA circuit provides an impedance match and also serves to isolate the modem and the computer from transient signals and other disturbances coming in over the phone line. The DAA also protects the phone line from disabling influences emanating from the computer or the modem.
For example, damage would occur to the telephone system if instead of transmitting frequency signals, DC power was transmitted over the phone lines. Because the modem is attached directly to the phone line, the modem must incorporate the required FCC interface and must comply with any requirements imposed by local telephone companies.
The ubiquity of the telephone and the need for interactive systems throughout the world have caused standards to be established for the components of a telephonic system. Standardization allows telephone systems and devices using those systems to be interchangeable. The components of the telephone that are most thoroughly standardized are physical/electrical media connectors.
Physical/electrical media connectors are used by almost all telephone companies throughout the world for many applications, the most important of which is interconnection of telephones with telephone lines. For this reason, stringent standardization of connectors is required if compatibility and interactivity is to be realized.
One popular physical/electrical media connector used in the United States of America is the RJ-11 6-position miniature modular plug physical/electrical media connector. The RJ-11 is used between the telephone line and the telephone itself.
Unfortunately, because of the physical and electrical differences between the many pins of the peripheral ports associated with the central processing unit of a computer and the 6 pins of the RJ-11, direct physical or electrical connection of the RJ-11 to the computer is not possible.
Consequently, it has been found necessary to employ modems or similar input/output devices or cards to effect communication between computers and telephone lines. Modems reconfigure binary data from the central processing unit of the computer as received through the multi-pin peripheral port. The reconfigured data is then transmitted in analog form through the RJ-11 physical/electrical media connector into the telephone line.
B. Local Area Networks
In contradistinction to the development of telephone lines, transmission lines used in LANs have been developed specifically for the transmission of computer generated signals. Because of the recent development of these transmission lines, a variety of internal configurations for transmission lines have been developed to accomplish the transmission of computer data between computers.
Three basic cable types are available for use in transmitting encoded signals from one place to another: (1) coaxial, (2) twisted-pair, and (3) fiber optic. Each has certain advantages and disadvantages.
1. Coaxial Cable
Originally, access protocols used in LANs were tied to cable type. For example, Ethernet.RTM. and ARCnet.RTM., two of the original LAN systems, ran only on coaxial cable. Because these protocols have been around the longest, the majority of installed LANs use coaxial cable.
Coaxial cable has four components. The first is an inner conductor--a solid metal wire. This inner conductor, is surrounded by an insulation layer. A third layer, comprised of a thin tubular piece of metal screen, surrounds the insulation. The axis of curvature of the screen coincides with that of the inner conductor; hence, the term "coaxial" has developed. Coaxial cable also has applications in cable television connection and in automotive radio installations. Coaxial cable ranges in size from thick Ethernet.RTM. (which is as thick as one-half inch) to Thinnet.RTM. (which resembles cable television cable).
The advantages of coaxial cable include high bandwidth which allows it to carry signals at high speeds, relatively low susceptibility to interference, and familiarity to LANs installers.
The main disadvantage to coaxial cable is the difficulty in connecting it to LANs. Standard Ethernet.RTM. coaxial cable requires a connection commonly referred to as a vampire tap and drop cable. This connection is bulky and adds to the already high expenses incurred with the acquisition of the coaxial cable.
2. Twisted-pair Cable
Although coaxial cable has been used in LANs longer than other cable types, twisted-pair cable has been used in the communications industry longer than coaxial cable in other applications such as telephone lines. Because early experiments with twisted-pair cable resulted in slow transmission rates, coaxial cable was selected for use with LANs requiring high transmission rates. Recent advances in LANs protocols have increased the transmission rate possible with twisted-pair cable to the point that twisted pair cable is now a viable alternative to coaxial cable.
The benefits to using twisted-pair cable revolve around the availability of twisted-pair cable in almost every building constructed offering telephone service. By utilizing the twisted-pair cable already installed in buildings for telephone lines, twisted-pair cable enjoys a significant cost advantage over coaxial cable in retrofit situations. In addition, twisted-pair cable is more flexible and is easier to install in new buildings.
Due to the size and configuration of twisted-pair cable, a variety of physical/electrical media connectors may be utilized. Physical/electrical media connectors complying with FCC Rule 68.500, subpart F, such as RJ-type connectors are easily used with twisted-pair cable. As a result, one of the most advantageous features of twisted-pair cable is its connectability.
3. Fiber Optic Cable
Fiber optic cable is immune to electromagnetic interference, has enormous bandwidth, sends data over huge distances, and can carry voice, video, and data. The biggest disadvantages of fiber optic cable are the price and the difficulty in connecting it to LANs. Fiber optic connectors are more difficult to install than even coaxial connectors.
Of the variety of transmission lines available, unshielded twisted pair cable seems to be emerging as the most popular variety of computer data transmission cable. Contributing to the popularity of this variety of cable at least in part, is the compatibility of this cable with a broad range of physical/electrical media connectors.
4. LAN Configurations
A typical local area network comprises several computers at remote locations throughout a building interconnected with unshielded twisted pair cable utilizing RJ-type physical/electrical media connectors. The network is typically connected to a file server. A file server is a computer providing shared access to a file system, printer, electronic mail service, or modem. The file server is a combination of hardware and software that contains files shared by everyone connected to the LAN.
As LANs utilizing unshielded twisted pair cable are capable of transmitting signals at a higher rate than signals travelling through telephone lines, the requirements of the devices used to translate and reconfigure signals from the computer for transmission through lines have consequently been developed with different requirements.
The counterpart to the modem in telephonic communications is the LAN adapter card or data communications card. In a similar fashion to a modem, these communications cards reconfigure the parallel data produced by the computer into a serial form and back. These cards also provide buffering, encoding and decoding, cable access, and transmission.
As the use of LANs increases, it has become increasingly more beneficial for users of portable computers to have the ability to interact with several local area networks at different locations. For example, information at one location may be downloaded to a portable computer that allows a user to manipulate the data during a business trip and load the manipulated data onto the network at a destination. Diagnostics and maintenance are also made easier through the use of common connectors.
As the popularity of twisted-pair cable has increased, the popularity of the most frequently used physical/electrical media connector, the 8-pin miniature modular plug, has also increased. This increase in popularity of the 8-pin miniature modular plug has introduced the same problems and solutions into LANs as will be discussed regarding the RJ-11 physical/electrical media connector in the development of modems.
C. Modem Development
1. External Modems
Many modems in use today are configured as external accessory units, housed in their own cases, and attached to the computer. Such a prior art modem is illustrated in FIG. 1 of the drawings. A modem 10 is shown near a telephone base 12 which cradles a telephone receiver 14. Modem 10 is electrically connected to the telephone with a telephone extension line utilizing physical/electrical media connectors at each end. Signals transmitted by a modem at a remote location are received over a telephone line 16. An RJ-11 physical/electrical media connector 18 is used to physically and electrically connect a local telephone extension line 20 to telephone line 16. Another RJ-11 connector is used to connect extension line 20 to modem 10.
Modem 10 converts the modem frequency signal back to binary digital data characters. The digital characters are then transmitted through a multiplexed cable 22 to an input port of a receiving computer 24. In the prior art system illustrated in FIG. 11, a DAA circuit is located within modem 10 at the point where the modem interfaces with telephone extension line 20. At this location, the DAA circuit isolates the modem and the computer from disturbances coming in or going out over the phone line.
External modems like modem 10 are often employed by users of personal computers. External modems have been popular because they can easily contain a substantial amount of electronic circuitry or hardware, as well as executable programs or software.
With the advent of downsizing technology in other computer components, however, smaller portable computers (often referred to as laptop or notebook computers) have taken the place of many of the desktop models. With the new-found portability available with laptop or notebook computers, the size of external modems has made external modems cumbersome and not in keeping with the portability that buyers of these downsized computers desire.
D. Integral Modems
To overcome the inconvenience and physical limitations of external modems, smaller modems have been developed that are small enough to be built into the housing of a portable computer. Such a modem is illustrated in FIG. 2. An integral internal modem 30 is located within the housing of a portable computer 32 at a position giving access to local telephone extension line 20. The interface between the telephone line and modem 30 is achieved through the use of an RJ-11 physical/electrical media connector and an internal DAA 34. The RJ-11 physical/electrical media connector has two components: an RJ-11 socket and an RJ-11 plug.
An RJ-11 socket 36 is formed in the housing of computer 32. This socket is capable of receiving an RJ-11 plug 38 from any of the many telephone lines utilizing an RJ-11 physical/electrical media connector system.
The ubiquity of the RJ-11 system provides users of portable computers with internal modems a uniform standard interface for media access devices such as modems. Modem manufacturers can build products capable of accepting the RJ-11 media connector with confidence that their product can be used in a wide geographical area. Because modems can be built to the RJ-11 uniform standard, consumers benefit from the ability to interchange and interconnect media access devices without the need for adapters for products made by different manufacturers.
E. Communications Cards
As computer housings have continued to be downsized, internal spatial restrictions have required the establishment of standards for the internal accessories of the computer. One set of standards applicable to memory cards has been developed by the Personal Computer Memory Card International Association (PCMCIA). This organization is comprised of hundreds of manufacturers of memory cards and related peripheral equipment. The PCMCIA has determined that the spatial standard for all memory cards used in down-sized computers should be restricted to a rectangular space approximately 55 mm in width, 85 mm in length, and 5 mm in depth.
In keeping with the PCMCIA standards for memory cards, internal modem manufacturers have adopted the same spatial standards for use with their down-sized communications cards. By complying with the standards established by PCMCIA for memory cards, communications card manufacturers have assured themselves of compatibility and spatial conformity with computers utilizing the new PCMCIA standards.
The constraints imposed by this new PCMCIA standard have resulted in the development of "credit card" communications cards. Most of the components formerly housed within a modem are now contained within a credit card-sized wafer. One communications card conforming to this new PCMCIA standard is produced by Intel under the ExCA.RTM. trademark and is similar to that illustrated in FIG. 3.
Although the communications card illustrated serves the functions of a modem, a similar card has been contemplated for use in LANs.
FIG. 4 illustrates 68 pin socket 42 which is pressed over a corresponding plug affixed to the circuit board of the computer. This plug and socket arrangement provides versatility in the selection of cards that a user may select for use with the computer. For example, extra memory cards also utilize the same PCMCIA architecture standards and may therefore be inserted over the same plug as is used with communications card 40.
FIG. 5 illustrates peripheral socket 44 in PCMCIA communications card 40. Although 68 pin socket 42 is part of the standardized electrical interface under the PCMCIA architecture, socket 44 is built into communications card 40 to correspond to the variety of plugs employed by different manufacturers. For example, socket 44 is used to interface with external media access units that contain elements of integrated modems that have not been included within PCMCIA communications card 40.
Elements not included within the communications card illustrated in FIG. 5 include the RJ-type connector interface and the DAA. The DAA and the connector interface used in the system illustrated in FIG. 5 media are housed in an external unit (often referred to as an "intermediate physical/electrical connector" or "podule"). While 68 pin socket 42 is standardized as part of the PCMCIA architecture, the shape and configuration of peripheral socket 44 varies with the needs of the manufacturers of the external intermediate physical/electrical connectors.
FIG. 6 illustrates another form of peripheral socket like that illustrated in FIG. 5. External intermediate physical/electrical connector socket 46 has a shape capable of receiving a corresponding plug for use with the DAA and RJ-11 interface housed in a podule for modem transmissions or an 8 pin modular plug interface for use with LANs. Socket 46 is specific external DAA and RJ-11 interface podule. As a result, although the RJ-11 media connector is available at most locations providing telephone service, a user will still be unable to utilize an integral modem if a compatible external DAA and RJ-11 interface podule corresponding to socket 46 is not available.
FIG. 7 depicts communications card 40 inside of a down-sized or laptop computer. External intermediate physical/electrical connector socket 46 is shown incorporated into communications card 40 and extending to an exposed position so that connection can be made therewith. An intermediate physical/electrical connector podule 48 houses an external DAA 50 and RJ-11 enclosed socket 36. Podule 48 is in electrical connection with communications card 40 through an external physical/electrical connector plug 52 and a connector cord 54.
In use, a telephone line is physically and electrically connected to RJ-11 enclosed socket 36 with an RJ-11 plug to form a communications interface. Incoming signals are then filtered through external DAA 50 and pass through connector cord 54 to external physical/electrical connector plug 52. A second communications interface is formed between connector plug 52 and connector socket 46. As discussed previously, the RJ-11 communications interface is widely available, while the second communications interface between connector plug 52 and connector socket 46 is manufacturer-specific.
After passing through the second communications interface, signals are translated from analog modem frequency to binary signals compatible with the computer.
The depth of a PCMCIA standard communications card is limited to 5 mm. However the depth of a media connector such as the RJ-type or 8-pin miniature modular plug is approximately 8-12 mm. As a result, an RJ-11 or other modular connector exceeds the depth restrictions imposed by the PCMCIA standards for internal computer components. Direct internal connection of the physical/electrical media connector would necessitate encroaching on a neighboring card space--an approach advocated by some manufacturers, but requiring the sacrifice of space that could be used to provide additional memory capacity.
While an external DAA and adaptor solve the problem of incompatibility between computers and modems or LANs, the solution necessitates carrying an extra item (namely the external DAA podule) whenever use of the modem is desired. The advantages of easy portability afforded by downsized computers are somewhat negated by the need to carry along extra interfacing devices.
A second problem encountered by users of external DAA's is that there is no standardization among the various manufacturers of external DAA's. As a result, intermediate forms, no one form allowing use of an external DAA made by a different manufacturer. It is, therefore, imperative that an appropriate external DAA is carried along whenever the computer is transported to a different location. As no direct interface with the communications card is afforded without the adaptor, failure to remember the adaptor results in an essentially nonfunctional communications system or LAN.
Another solution advocated by some manufacturers to the incompatibility of the RJ-11 connector with the PCMCIA memory card size constraints is illustrated in FIG. 8. PCMCIA communications card 40 is shown with an integrated physical/electrical connector 56 attached at the location where enclosed socket 44 is usually located. A small DAA is located within integrated connector 56 to filter signals passing therethrough. RJ-11 connector socket 36 is formed in a free end of connector 56. The height of connector 56 is approximately 10 mm, thereby allowing RJ-11 socket 36 to be contained therein. Incorporation of integrated connector 56 allows an 8 mm RJ-11 plug to interface with the 5 mm communications card 40.
FIG. 9 illustrates the communications card and connector of FIG. 8 installed in a laptop computer. 68 pin socket 42 is installed over a corresponding plug in electrical communication with the circuit board of the computer. Although communications card 40 complies with the 5 mm PCMCIA size restrictions, the 10 mm integrated connector 56 does not. As a result, integrated connector 56 must either be placed outside of the computer housing or must displace memory cards in adjoining slots.
Operation of the communications card requires only the connection of an RJ-11 plug into RJ-11 enclosed socket 36 or an RJ-45 or 8 pin modular plug for use in LANs. Signals received from remote modems are filtered by the internal DAA and converted by communications card 40.
Although this solution to the RJ-11 LAN interface problem eliminates the need for carrying extraneous components and eliminates the incompatibility of those components, some problems unique to the integral physical/electrical connector are introduced.
For example, the extension of integral connector 56 beyond the housing of the computer exposes the connector to the possibility of breakage even when the connector is not in use. The protrusion beyond the normal dimensions of the computer also interferes with the fit of computer portfolios used in transporting many laptop computers.
It would, therefore, be an advancement in the art to provide a 5 mm PCMCIA-architecture communications card that is capable of direct connection with a miniature modular plug physical/electrical media connector.
Yet another advancement in the art would be to provide a direct media connector interface for use in laptop and notebook computers that does not displace contiguous memory cards.
A further advancement in the art would be to provide a communications card that complies with the 5 mm PCMCIA memory card space configuration limitations while also providing direct connection with a miniature modular plug physical/electrical media connector.
A still further advancement in the art would be to provide a communications card that allows the computer housing to retain its designed shape free from any added protrusions or added external equipment.
Another advancement in the art would be to provide a 5 mm PCMCIA-architecture communications card/media connector interface that is capable of being carried internally when not in use.
Still another advancement in the art would be to provide a communications card/media connector interface that is free from reliance on an enclosed physical/electrical media connector socket.
A further advancement in the art would be to provide a communications card connecting system that is free from reliance upon an external Data Access Arrangement circuit.
A still further another advancement in the art would be to provide a communications card connecting system that is free from reliance on any components which must be carried externally in addition to the computer.
Another advancement in the art would be to provide a LAN adaptor card capable of direct connection with a miniature modular plug physical/electrical media connector.
Still another advancement in the art would be to provide a LAN adaptor card that is capable of being carried internally in the computer when not in use.
Yet another advancement in the art would be to provide a LAN adaptor card connecting system that is free from reliance on any components which must be carried externally in addition to a portable computer.